In many circumstances, measuring a person's emotional state and/or emotional response to various stimuli may provide valuable information. For example, when marketers, researchers, or other entities desire information relating to emotional responses, various stimuli may be presented to a subject to evaluate an emotional response to the presented stimuli. In general, the stimuli presented to subjects may include a visual stimulus, such as still or moving images, slides, and/or videos. As used herein, a “subject” may generally include, for example, an individual respondent, person, or other test subject for which emotional response data may be desired. In any particular data collection, analysis, or other session testing for emotional responses, subjects may participate actively (e.g., responding to instructions, viewing and responding to various stimuli, etc.) or passively (e.g., collecting data from an unaware subject). As used herein, “emotional response testing” may generally include a variety of activities during one or more test stimuli are presented to a subject to determine the subject's emotional response to the test stimuli (e.g., advertising and/or marketing studies, voter polling, and/or other testing).
Recently, the assignee of the present application has developed a tool referred to as the Emotion Tool™, which provides objective and non-intrusive techniques for evaluating a subject's emotional response and visual attention to stimuli such as print ads, market research materials, brochures, or other stimuli. Some of the techniques for evaluating a subject's emotional response may include measuring and processing various forms of eye data for the subject (e.g., pupil dilation, blink rate, eye movement, etc.). For example, visual stimuli may be presented to the subject on a computer monitor having an eye-tracking device coupled thereto. The eye-tracking device may therefore be used to collect raw eye data from the subject, and the raw eye data may be processed to provide a psycho-physiological interpretation of an emotional response to the presented stimuli. Further details and examples relating to this tool and the techniques used therein can be found in U.S. Patent Application Publication No. 2007/0066916, the disclosure of which is hereby incorporated by reference in its entirety.
Although performing certain calibration steps prior to emotional response testing may generally be known, existing calibration techniques typically focus primarily on gaze tracking (e.g., tracking a location where a subject may be looking at a given moment). Existing techniques for calibrating gaze tracking typically involve presenting a series of indicators at different positions on a monitor (e.g., white circles on a black background), and determining where on the monitor the subject is looking relative to the position of each of the indicators. However, simply calibrating for gaze fails to appreciate that different test subjects can often have different emotional profiles and/or different emotional states at the time of testing (e.g., accurately evaluating a subject's emotional response to a stimulus may depend on whether the subject was happy, angry, confused, or in another emotional state when the test began). Existing techniques that seek to compensate for an initial or preexisting emotional state have focused on attempting to induce a neutral emotional state prior to beginning an emotional response test (e.g., presenting a presumptively neutral slide to the subject to induce the neutral emotional state).
However, these techniques have a limited effect. For example, in some circumstances, merely attempting to induce a neutral emotional state can lead to flawed test results due to differences among test subjects relating to, among other things, emotional profiles, responses to the presumptively emotionally neutral stimuli, ocular physiological characteristics (e.g. pupil size, pupil dilation range, response time, blink characteristics, eye movement characteristics), and/or other differences. For example, where different test stimuli have different light intensity values, various test subjects may experience different physiological responses to the intensity of the stimuli (e.g. pupil dilation may vary from one subject to another). This may be thought of as a light reflex, which is a physical reaction as opposed to an emotional response. In another example, problems can arise because various subjects may look at different portions of a monitor before test stimuli are shown, or worse, subjects may look away from the monitor altogether. These variations, among others, can often lead to errors in the measurement of emotional response.
Existing and known techniques for calibrating and normalizing eye data to be used in emotional response testing suffer from these and other drawbacks.